Abstract [en]

A total artificial heart (TAH) is typically used to bridge the time to heart transplantation. A device designed by Robert Jarvik has been improved through the years and under the name of Syncardia™ this has been the most successful commercially available TAH so far. Since 2008 the Carmat™ heart has been under development in Europe. The Scandinavian Real Heart™ is based on a unique physiological concept where the atrio-ventricular valve plane is of utmost importance in the pumping function of the heart. It consists of two identical parts driven separately by independent motors and in this first animal study we have used one part as a left ventricular assist device. This new concept makes the device flexible as it may be used not only as a TAH but also as a separate pump for left or right ventricular assist.

Abstract [en]

BACKGROUND: The purpose of this study was to report the use of a transvenous transseptal approach using a stent valve in patients with degenerated biological mitral valve prostheses, regurgitation after mitral repair, and native mitral stenosis.

RESULTS: The procedure was initially successful in all patients. Predilation was performed for balloon sizing only in the 2 patients with native mitral stenosis. The stent valve was deployed during 1 period of rapid pacing. A guidewire, as a loop from the right femoral vein and through the left ventricular apex, facilitated a good angle and secure positioning of the stent valve. An ultrasonographically guided puncture of the apex was carried out in 6 patients, and in the other 4 we performed a minithoracotomy before apical puncture. All valves were implanted in a good position with improved function and without significant paravalvular leakage (PVL). There were no periprocedural deaths. The 30-day survival was 80% (8 of 10 patients), and 60% (6 of 10) of patients were still alive a median time of 290 days after the procedure.

CONCLUSIONS: Transvenous transseptal implantation of a stent valve was performed in 10 patients with mitral valve disease, with good early functional results. These high-risk patients must be carefully selected by a multidisciplinary team because the procedure carries a high mortality.

Abstract [en]

We used a modified combination of the transseptal and transapical methods to facilitate the controlled delivery and use of a stent valve in a patient with calcified native mitral stenosis. A loop from the right femoral vein passing transseptally and then through the apex of the left ventricle was created, enabling highly controlled positioning and deployment of the stent valve.

Davidsson, Bo

Abstract [en]

Introduction: student perception of problem-based learning (PBL) group tutorials was investigated at a Swedish University Medical College 27 years after the introduction of PBL into the curriculum.

Methods: a survey questionnaire comprising 43 questions answered on a Likert-type scale, together with one open question was used. The questionnaire was distributed to all 821 students taking part in the Linköping University medical program at the beginning of the Spring Term 2013. The results were subjected to explorative factor analysis, descriptive statistics and ANOVA. Responses to the open question where analyzed qualitatively by categorization.

Results: 84 per cent of the 821 students completed the survey. Four factors describing student perception were identified: 1) PBL as a method of learning; 2) the tutor’s role; 3) PBL, stress and feelings of insecurity; and 4) traditional teaching methods within the PBL curriculum. The Cronbach´s alpha value was 0,788 overall. Two hundred and seventy-six students answered the open question declaring that they would appreciate more precise aims and objectives, smaller tutorial groups, and more formal lectures.

Conclusions: the results of this study on PBL group tutorials, as seen from the student’s perspective, stress the importance of tutorial quality, tutor competence, tutorial group size and the quality and aims of the curriculum. Too much emphasis on the teacher’s research merits against the educational ones, and the inability to adapt to the needs and wishes of new generations of students seems a probable cause for the erosion of PBL.

Abstract [en]

Purpose

The continuous flow mechanical circulatory support HeartMate II™ (Thoratec Corporation, Inc. Pleasanton, USA) (HMII), generates an auditory signal (acoustic fingerprint) that can be registered by routine auscultation. A temporary or permanent change in sound indicates a change in pump function. Previous mock loop studies have shown that changes in acoustic fingerprint are due to changes in speed, so the aim of this study was to see if the acoustic fingerprint changed during an echocardiographic ramp test.

Methods

Four stable, event-free patients included in the SoundMate study performed an echocardiographic ramp test. The speed was increased stepwise by 400 rpm between 8 000 and 12 000 rpm, and the left ventricular end diastolic diameter, flow, power consumption and blood pressure were measured. Sounds from HMII were recorded using an iPhone™ (Apple Inc. Cupertino, CA, USA) with the stethoscope application iStethPro™ (Dr. Peter J Bentley, UK) and the frequency map analyzed using the Audacity™ program (Unicode, Ash, Chinen and Crook, USA). The acoustic fingerprint is divided into regions (R1: 1 000-6 500, R2: 8 500-14 000, R3: 15 000-21 000 Hz) and peaks (P1: 0-1 000, P2: 6 500-8 500, P4: 21 000-23 000 Hz) in order to facilitate calculations and clarify changes in frequency.

Results

There were significant (p<005) changes in the acoustic fingerprint when increasing the pump speed between 8 000 and 12 000 rpm. In 2/4 patients there were no significant changes in P1, otherwise there were significant changes in all regions and peaks. During the ramp test the power increased in mean 7 W, flow 3,1 L/min and the blood pressure measured with Doppler increased by ~15 mmHg. The left ventricular size decreased with ~2 cm.

Conclusion

The acoustic fingerprint changes with pump speed. This implies that when using sound check for detection of pump dysfunction, a new baseline should be set after every adjustment of speed.

Abstract [en]

Mechanical circulatory support technology is continually improving. However, adverse complications do occur with devastating consequences, for example, pump thrombosis that may develop in several parts of the pump system. The aim of this study was to design an experimental clot/thrombosis model to register and analyze acoustic signals from the left ventricular assist device (LVAD) HeartMate II (HMII) (Thoratec Corporation, Inc., Pleasanton, CA, USA) and detect changes in sound signals correlating to clots in the inflow, outflow, and pump housing. Using modern telecom techniques, it was possible to register and analyze the HMII pump-specific acoustic fingerprint in an experimental model of LVAD support using a mock loop. Increase in pump speed significantly (P less than 0.005) changed the acoustic fingerprint at certain frequency (0-23 000 Hz) intervals (regions: R1-3 and peaks: P1,3-4). When the ball valves connected to the tubing were narrowed sequentially by similar to 50% of the inner diameter (to mimic clot in the out-and inflow tubing), the frequency spectrum changed significantly (P less than 0.005) in P1 and P2 and R1 when the outflow tubing was narrowed. This change was not seen to the same extent when the lumen of the ball valve connected to the inflow tube was narrowed by similar to 50%. More significant (P less than 0.005) acoustic changes were detected in P1 and P2 and R1 and R3, with the largest dB figs. in the lower frequency ranges in R1 and P2, when artificial clots and blood clots passed through the pump system. At higher frequencies, a significant change in dB figs. in R3 and P4 was detected when clots passed through the pump system. Acoustic monitoring of pump sounds may become a valuable tool in LVAD surveillance.